Dr. Saumitra Mukherjee
Professor
Department of Geology & Remote sensing
School of Environmental sciences
Jawaharlal Nehru University, New Delhi
INDIA
Biography
PDF:
(Commonwealth
Fellow).
Remote
sensing
applications
in
Geology(Remote sensing of Water resources), Earth & Ocean Sciences,
The University of Liverpool, Liverpool, UK. • Ph.D: Geology, Banaras
Hindu University, Varanasi (Collaboration with IIRS) • PhD Topic
(Geology & Geochemistry of Pegmatites and Associated Rocks of
Jorasemar and Sapahitola Area District Bihar with special reference to
Applications of Remote Sensing Techniques in Exploration of Natural
Resources) September 1989, 365 Pages • M.Sc.: Geology, Banaras Hindu
University, Varanasi, 1st Div •
B.Sc. : Geology, Botany, Chemistry,
Banaras Hindu University, Varanasi, 1st Div • PGD: Environment &
Ecology, IIEE, New Delhi., 1st Div • Certificate: Remote Sensing & GIS,
RRSSC, IIT Kharagpur, West Bengal •
Certificate: Groundwater
Exploration and Management, CGWB, Govt.of India.
Research interest
Earth
Observation
Applications
for
Water
Resources
Assessment
and
Management. (Remote sensing and GIS applications in Ground w ater Exploration,
Rainwater Harvesting). Early warning of Natural Hazards and its relation with
Water resources(Tornado, Cyclone, Earthquake, Tsunami, Snowfall, Forest Fire).
Research guidance and publications in the following areas Monitoring, analyzing,
and quantifying components of the w ater cycle Monitoring/ Modeling real or
near-real time surface and/or subsurface hydrological processes A nalyzing
interactions of land surface and atmospheric processes Investigating w etland
dynamics Monitoring, forecasting and managing flooding and droughts
Monitoring land use/cover change and impact on hydrological processes
Determining effects of human activities on both the quantity and quality of water
Developing products for use in integrated w ater resources management. Used
Satellite data: IRS,LA NDSA T, SPOT (INDIA , UK, and A FRICA ), IRS (INDIA ),
RESOURSESAT and LIDAR Data (UK), SOHO data of Sun-Earth Environment.
General Description
Rainwater harvesting is a technology used for collecting and storing
rainwater from rooftops, the land surface or rock catchments using
simple techniques such as jars and pots as well as more complex
techniques such as underground check dams.
The techniques usually found in A sia and A frica arise from practices
employed by ancient civilizations within these regions and still serve
as a major source of drinking water supply in rural areas.
Commonly
used systems are constructed of three principal
components; namely, the catchment area, the collection device, and
the conveyance system.
In the present scenario management and distribution of w ater has become
centralized. People depend on government system, which has resulted in
disruption of community participation in water management and collapse of
traditional w ater harvesting system.
As the water crisis continues to become severe, there is a dire need of reform in
w ater management system and revival of traditional systems. Scientific and
technological studies needs to be carried out to assess present status so as to
suggest suitable mitigative measures for the revival to traditional system/ w isdom.
Revival process should necessarily be backed by people's initiative and active
public participation.
Living creatures of the universe are made of five basic elements, viz., Earth, Water,
Fire, A ir and Sky, Obviously, w ater is one of the most important elements and no
creature can survive w ithout it.
Extent of Use
The history of rainw ater harvesting in A sia can be traced back to about the
9th or 10th Century and the small-scale collection of rainw ater from roofs
and simple brush dam constructions in the rural areas of South and Southeast A sia.
Rainw ater collection from the eaves of roofs or via simple gutters into
traditional jars and pots has been traced back almost 2000 years in Thailand.
A thin layer of red clay is generally laid on the bottom
of the ponds to minimize seepage losses. Trees, planted
at the edges of the ponds, help to minimize
evaporative losses from the ponds.
Why harvest rainwater ?
This is perhaps one of the most frequently asked question, as to why one should harvest rainwater.
There are many reasons but following are some of the important ones.
To arrest ground water decline and augment ground water table
To beneficiate water quality in aquifers
To conserve surface water runoff during monsoon
To reduce soil erosion
To inculcate a culture of water conservation
How to harvest rainwater
Broadly there are two ways of harvesting
rainwater:
(i)
(ii)
Surface runoff harvesting
Roof top rainwater harvesting
Surface runoff harvesting:
In urban area rainwater flows away
as surface runoff. This runoff could be
caught and
used for recharging aquifers by adopting appropriate methods.
Roof top rainwater harvesting (RTRWH):
It is a system of catching rainwater where it falls. In rooftop harvesting, the roof becomes the
catchments, and the rainwater is collected from the roof of the house/building. It can either be
stored in a tank or diverted to artificial recharge system. This method is less expensive and
very effective and if implemented properly helps in augmenting the ground water level of the
area.
Precautionary Measures
Roof or terraces uses for harvesting should be clean, free from dust, algal plants etc.
Roof should not be painted since most paints contain toxic substances and may peel off.
Do not store chemicals, rusting iron, manure or detergent on the roof.
Nesting of birds on the roof should be prevented.
Terraces should not be used for toilets either by human beings or by pets.
Provide gratings at mouth of each drainpipe on terraces to trap leaves debris and floating materials.
Provision of first rain separator should be made to flush off first rains.
Do not use polluted water to recharge ground water.
Ground water should only be recharged by rainwater.
Before recharging, suitable arrangements of filtering should be provided.
Filter media should be cleaned before every monsoon season.
During rainy season, the whole system (roof catchment, pipes, screens, first flush, filters, tanks)
should be checked before and after each rain and preferably cleaned after every dry period exceeding
a month.
At the end of the dry season and just before the first shower of rain is anticipated, the storage tank
should be scrubbed and flushed off all sediments and debris.
Advantages
Rainwater harvesting technologies are simple to install and operate. Local people can
be easily trained to implement such technologies, and construction materials are also
readily available. Rainwater harvesting is convenient in the sense that it provides
water at the point of consumption, and family members have full control of their
own systems, which greatly reduces operation and maintenance problems. Running
costs, also, are almost negligible. Water collected from roof catchments usually is of
acceptable quality for domestic purposes. As it is collected using existing structures
not specially constructed for the purpose, rainwater harvesting has few negative
environmental impacts compared to other water supply project technologies.
Although regional or other local factors can modify the local climatic conditions,
rainwater can be a continuous source of water supply for both the rural and poor.
Depending upon household capacity and needs, both the water collection and
storage capacity may be increased as needed within the available catchment area.
Disadvantages
Disadvantages of rainw ater harvesting technologies are mainly due to
the limited supply and uncertainty of rainfall. A doption of this
technology requires a *bottom up* approach rather than the more usual
*top down* approach employed in other w ater resources development
projects. This may make rainw ater harvesting less attractive to some
governmental agencies tasked w ith providing w ater supplies in
developing countries, but the mobilization of local government and NGO
resources can serve the same basic role in the development of rainw aterbased schemes as w ater resources development agencies in the larger,
more traditional public w ater supply schemes.
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